VTTBuilder.h revision 1ec5750908039701b206fc32dd2b95c45cd5cce8 
1//===--- VTTBuilder.h - C++ VTT layout builder --------------------*- C++ -*-=//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This contains code dealing with generation of the layout of virtual table
11// tables (VTT).
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_CLANG_AST_VTTBUILDER_H
16#define LLVM_CLANG_AST_VTTBUILDER_H
17
18#include "clang/AST/BaseSubobject.h"
19#include "clang/AST/CXXInheritance.h"
20#include "clang/AST/GlobalDecl.h"
21#include "clang/AST/RecordLayout.h"
22#include "clang/Basic/ABI.h"
23#include "llvm/ADT/SetVector.h"
24#include <utility>
25
26namespace clang {
27
28class VTTVTable {
29  llvm::PointerIntPair<const CXXRecordDecl *, 1, bool> BaseAndIsVirtual;
30  CharUnits BaseOffset;
31
32public:
33  VTTVTable() {}
34  VTTVTable(const CXXRecordDecl *Base, CharUnits BaseOffset, bool BaseIsVirtual)
35    : BaseAndIsVirtual(Base, BaseIsVirtual), BaseOffset(BaseOffset) {}
36  VTTVTable(BaseSubobject Base, bool BaseIsVirtual)
37    : BaseAndIsVirtual(Base.getBase(), BaseIsVirtual),
38      BaseOffset(Base.getBaseOffset()) {}
39
40  const CXXRecordDecl *getBase() const {
41    return BaseAndIsVirtual.getPointer();
42  }
43
44  CharUnits getBaseOffset() const {
45    return BaseOffset;
46  }
47
48  bool isVirtual() const {
49    return BaseAndIsVirtual.getInt();
50  }
51
52  BaseSubobject getBaseSubobject() const {
53    return BaseSubobject(getBase(), getBaseOffset());
54  }
55};
56
57struct VTTComponent {
58  uint64_t VTableIndex;
59  BaseSubobject VTableBase;
60
61  VTTComponent() {}
62  VTTComponent(uint64_t VTableIndex, BaseSubobject VTableBase)
63    : VTableIndex(VTableIndex), VTableBase(VTableBase) {}
64};
65
66/// \brief Class for building VTT layout information.
67class VTTBuilder {
68
69  ASTContext &Ctx;
70
71  /// \brief The most derived class for which we're building this vtable.
72  const CXXRecordDecl *MostDerivedClass;
73
74  typedef SmallVector<VTTVTable, 64> VTTVTablesVectorTy;
75
76  /// \brief The VTT vtables.
77  VTTVTablesVectorTy VTTVTables;
78
79  typedef SmallVector<VTTComponent, 64> VTTComponentsVectorTy;
80
81  /// \brief The VTT components.
82  VTTComponentsVectorTy VTTComponents;
83
84  /// \brief The AST record layout of the most derived class.
85  const ASTRecordLayout &MostDerivedClassLayout;
86
87  typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy;
88
89  typedef llvm::DenseMap<BaseSubobject, uint64_t> AddressPointsMapTy;
90
91  /// \brief The sub-VTT indices for the bases of the most derived class.
92  llvm::DenseMap<BaseSubobject, uint64_t> SubVTTIndicies;
93
94  /// \brief The secondary virtual pointer indices of all subobjects of
95  /// the most derived class.
96  llvm::DenseMap<BaseSubobject, uint64_t> SecondaryVirtualPointerIndices;
97
98  /// \brief Whether the VTT builder should generate LLVM IR for the VTT.
99  bool GenerateDefinition;
100
101  /// \brief Add a vtable pointer to the VTT currently being built.
102  void AddVTablePointer(BaseSubobject Base, uint64_t VTableIndex,
103                        const CXXRecordDecl *VTableClass);
104
105  /// \brief Lay out the secondary VTTs of the given base subobject.
106  void LayoutSecondaryVTTs(BaseSubobject Base);
107
108  /// \brief Lay out the secondary virtual pointers for the given base
109  /// subobject.
110  ///
111  /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base
112  /// or a direct or indirect base of a virtual base.
113  void LayoutSecondaryVirtualPointers(BaseSubobject Base,
114                                      bool BaseIsMorallyVirtual,
115                                      uint64_t VTableIndex,
116                                      const CXXRecordDecl *VTableClass,
117                                      VisitedVirtualBasesSetTy &VBases);
118
119  /// \brief Lay out the secondary virtual pointers for the given base
120  /// subobject.
121  void LayoutSecondaryVirtualPointers(BaseSubobject Base,
122                                      uint64_t VTableIndex);
123
124  /// \brief Lay out the VTTs for the virtual base classes of the given
125  /// record declaration.
126  void LayoutVirtualVTTs(const CXXRecordDecl *RD,
127                         VisitedVirtualBasesSetTy &VBases);
128
129  /// \brief Lay out the VTT for the given subobject, including any
130  /// secondary VTTs, secondary virtual pointers and virtual VTTs.
131  void LayoutVTT(BaseSubobject Base, bool BaseIsVirtual);
132
133public:
134  VTTBuilder(ASTContext &Ctx, const CXXRecordDecl *MostDerivedClass,
135             bool GenerateDefinition);
136
137  // \brief Returns a reference to the VTT components.
138  const VTTComponentsVectorTy &getVTTComponents() const {
139    return VTTComponents;
140  }
141
142  // \brief Returns a reference to the VTT vtables.
143  const VTTVTablesVectorTy &getVTTVTables() const {
144    return VTTVTables;
145  }
146
147  /// \brief Returns a reference to the sub-VTT indices.
148  const llvm::DenseMap<BaseSubobject, uint64_t> &getSubVTTIndicies() const {
149    return SubVTTIndicies;
150  }
151
152  /// \brief Returns a reference to the secondary virtual pointer indices.
153  const llvm::DenseMap<BaseSubobject, uint64_t> &
154  getSecondaryVirtualPointerIndices() const {
155    return SecondaryVirtualPointerIndices;
156  }
157
158};
159
160}
161
162#endif
163